T-cell and B-cell dynamics following prime-boost immunization with W135 meningococcal conjugate vaccine in mice

Glycoconjugate vaccines convert T-cell-independent polysaccharides into T-cell-dependent antigens, but the cellular dynamics of prime‑boost responses remain incompletely defined.

Mice were immunized with the W135 meningococcal conjugate vaccine (PSW135‑TT), unconjugated PSW135, or TT alone in a two‑dose regimen given at a 2‑week interval. B‑cell and T‑cell responses were evaluated at multiple time points after each immunization.

PSW135‑TT accelerated PSW135‑specific IgG class switching and maintained higher IgM levels compared to PSW135 alone, with an IgG1‑dominant profile consistent with a Th2‑biased humoral response. The conjugate induced more sustained B‑cell activation across tissues and a splenic plasmablast/early plasma cell peak that coincided with antibody appearance. T‑cell analysis revealed repeated waves of early CD4⁺ T‑cell activation in blood and a triphasic late activation pattern in spleen after PSW135‑TT, suggesting prolonged activation; CD8⁺ T‑cell activation after booster was also observed. Nonspecific stimulation showed overall Th2 bias, whereas antigen‑specific restimulation induced a Th1‑dominant recall response; a late Th17 increase was observed only in the conjugate group.

Thus, PSW135‑TT modulates B‑cell and T‑cell responses, supporting its potential as a vaccine candidate against W135 meningococcal disease.